Turbomachine Anti-Surge System

ABSTRACT

The subject matter of this specification can be embodied in, among other things, a compressor anti-surge system that includes a first actuator configured to actuate a first valve of a first turbomachine, and a first controller at least partially integrated with the first actuator or the first valve, and comprising circuitry configured to perform at least one of a control operation or a protection operation for the first turbomachine.

TECHNICAL FIELD

This specification relates to turbomachine control and protectionsystems.

BACKGROUND

Compressors increase the pressure on a fluid. As gases are compressible,the compressor also reduces the volume of a gas. A compressor stall is alocal disruption of the airflow in a gas turbine or turbochargercompressor. Axi-symmetric stall, also known as compressor surge, is abreakdown in compression resulting in a reversal of flow and the violentexpulsion of previously compressed gas out in the direction of thecompressor intake. This condition is a result of the compressor'sinability to continue working against the already-compressed gas behindit. As a result, the compressor may experience conditions that exceedits pressure rise capabilities, or the compressor may become loaded suchthat a flow reversal occurs, which can propagate in less than a secondto include the entire compressor.

Once the compressor pressure ratio reduces to a level at which thecompressor is capable of sustaining stable flow, the compressor willresume normal flow. If the conditions that induced the stall remains,the process can repeat. Repeating surge events can be dangerous, sincethey can cause high levels of vibration, compressor component wear andpossible severe damage to compressor bearings, seals, impellers andshaft, including consequential loss of containment and explosion ofhazardous gas.

SUMMARY

In general, this document describes turbomachine protection systems.

In a first aspect, a compressor anti-surge system includes a firstactuator configured to actuate a first valve of a first turbomachine,and a first controller at least partially integrated with the firstactuator or the first valve, and comprising circuitry configured toperform at least one of a control operation or a protection operationfor the first turbomachine.

Various embodiments can include some, all, or none of the followingfeatures. The first actuator can be configured to actuate the firstvalve through a mechanical coupler or a fluid circuit. The compressoranti-surge system can include a first field sensor configured to sense afirst turbomachine parameter of the first turbomachine, wherein thefirst controller is further configured to receive the first turbomachineparameter from the first field sensor and perform at least one of acontrol operation or a protection operation for the first turbomachine,based at least in part on the received first turbomachine parameter. Thevalve can be a sliding stem turbomachinery control valve, rotaryturbomachinery control valve, or a guide vane. The compressor anti-surgesystem can include an integral or adjacent heat exchanger in fluidcommunication with the valve and configured to cool fluids that arepassed through the valve. The first controller can include a firstcommunication port and can be configured to provide controlleroperations information through the first communications port, a secondactuator configured to actuate a second valve of a second turbomachine,and a second controller at least partially integrated with the secondactuator or the second valve, a second communication port configured tocommunicate with the first communication port and receive controlleroperations information, and comprising circuitry configured to performat least one of a control operation or a protection operation for thesecond turbomachine based at least in part on the received controlleroperations information. The first controller can include a firstcommunication port and is configured to provide controller operationsinformation through the first communications port, a second actuatorconfigured to actuate a second valve of the first turbomachine, and asecond controller at least partially integrated with the second actuatoror the second valve, a second communication port configured tocommunicate with the first communication port and receive controlleroperations information, and comprising circuitry configured to performat least one of a control operation or a protection operation for thefirst turbomachine based at least in part on the received controlleroperations information.

In a second aspect, a method of responding to compressor surge includesreceiving at a first controller at least partially integrated with afirst valve and from a first field sensor a first turbomachine parameterof a first turbomachine, determining by the first controller at leastone of a control operation or a protection operation for the firstturbomachine, based at least in part on the received first turbomachineparameter, and actuating by a first actuator at least partiallyintegrated with the first valve or the first controller the first valveto perform the determined control operation or protection operation forthe first turbomachine.

Various implementations can include some, all, or none of the followingfeatures. The first actuator can be configured to actuate the firstvalve through a mechanical coupler or a fluid circuit. The valve can bea sliding stem turbomachinery control valve, rotary turbomachinerycontrol valve, or a guide vane. At least one of the control operation orthe protection operation for the first turbomachine can includeactuating the first valve to control flow of fluids to an integral oradjacent heat exchanger in fluid communication with the valve andconfigured to cool fluids that are passed through the valve. The methodcan include providing by the first controller operations informationthrough a first communications port, receiving at a secondcommunications port of a second controller at least partially integratedwith a second valve of a second turbomachine or a second actuatorconfigured to actuate the second valve the controller operationsinformation, and actuating by the second actuator the second valveperform at least one of a control operation or a protection operationfor the second turbomachine based at least in part on the receivedcontroller operations information. The method can include providing bythe first controller operations information through a firstcommunications port, receiving at a second communications port of asecond controller at least partially integrated with a second valve ofthe first turbomachine or a second actuator configured to actuate thesecond valve the controller operations information, and actuating by thesecond actuator the second valve perform at least one of a controloperation or a protection operation for the first turbomachine based atleast in part on the received controller operations information.

The systems and techniques described here may provide one or more of thefollowing advantages. First, a system can widen the turbomachineoperating envelope. Second, the system can increase turbomachine safety.Third, the system can reduce of the effective valve size. Fourth, thesystem can reduce process time lags in the anti-surge system. Fifth, thesystem can improve the reliability and predictability of turbomachinesystem dynamic performance.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram that shows an example of a prior artturbomachine system

FIG. 2 is a schematic diagram that shows an example of a compressorsystem.

FIG. 3 is flow chart that shows an example of a process for protecting aturbomachine system.

DETAILED DESCRIPTION

This document describes systems and techniques for reducing turbomachinesurge. In general, the turbomachine anti-surge systems described in thedescriptions of FIGS. 2-3 combine all or some of one or more fast, highdynamic performance electrically actuated anti-surge valves, electroniccontrols fully or partially integrated into the valve assembly andexecuting surge prevention and surge protection control algorithms,compact heat exchangers adjacent to the anti-surge valves to cool themedium flowing through the anti-surge valves, and reducing process timelag in the anti-surge control loop.

Compressor systems, as commonly used in gas transmission compressorstations, petro-chemical refining and processing installations, forexample, can undergo a potentially destructive phenomenon called“surge”. The operational status of compressor systems can be representedby an operating map with axes representing changes in pressure (deltaP)and changes in flow (deltaQ). Surge occurs when, at a certain compressorhead, the flow-rate is reduced to the extent that the operatingconditions approach the points along the operating map wheredeltaP/deltaQ=0. These points appear on the operating map as a linesometimes referred to as the “surge line”. Upon further reduction of theflow-rate, the operating point of the compressor will oscillate betweena point left and right of this surge line. The oscillation can causeundesired motion of the compressor blades and the drive shaft such thatthe blades contact the stators within the compressor which can causecatastrophic damage in a very short time period.

FIG. 1 is a schematic diagram that shows an example of a prior artturbomachine system 100. In FIG. 1, the turbomachine system 100 isillustrated as a centrifugal compressor that includes a compressor 102 aand a compressor 102 b that are driven by a prime mover 104 (e.g., amotor). The compressors 102 a, 102 b pressurize a gas received at aninlet 106 (e.g., a suction port) and discharge the pressurized gas at adischarge 108 (e.g., an outlet port). A process gas cooler 107 (e.g., aheat exchanger) cools the gas before it flows out a discharge 109.

To prevent surge conditions, the system 100 commonly includes acontroller 110, a hot recycle valve 112 controlling forward flow along ahot recycle conduit 114, a cold recycle valve 116 controlling returnflow along a cold recycle conduit 118, and an actuator bypass loop witha gas inter-cooler 107 (heat exchanger). A fluid actuator 113 (e.g.,hydraulic, pneumatic) is configured to actuate the hot recycle valve112, and a fluid actuator 117 is configured to actuate the cold recyclevalve 116.

The controller 110 is configured to monitor either one or a plurality ofa collection of surge parameter values. The surge parameter values arebased on measurement signals received from a collection of systemsensors and feedback devices. In the illustrated example, the controller110 receives measurement signals from a flow sensor 130 a, a suctionpressure sensor 130 b, and a discharge pressure sensor 130 c.

If the controller 110 determines that a surge event is occurring, thecontroller 110 may directly or indirectly control a safeguard operation.For example, the controller 110 may trigger compressed gas at thedischarge 108 to flow back to the inlet 106 through the cold recyclevalve 116 to relieve the surge condition. In another example, thecontroller 110 may trigger uncompressed gas at the inlet 106 to flowforward to the discharge 108 through the hot recycle valve 112 torelieve the surge condition.

FIG. 2 is a schematic diagram that shows an example of a compressorsystem 200. In FIG. 2, the turbomachine system 200 is illustrated as acentrifugal compressor that includes a compressor 202 a and a compressor202 b that are driven by a prime mover 204 (e.g., a motor). Thecompressors 202 a, 202 b pressurize a gas received at an inlet 206(e.g., a suction port) and discharges the pressurized gas at a discharge208 (e.g., an outlet port). A process gas cooler 207 (e.g., a heatexchanger) cools the gas before it flows out a discharge 209.

A flow sensor 230 a is configured to measure inlet gas flow. A suctionpressure sensor 230 b is configured to measure gas pressure at the inlet206. A discharge pressure sensor 230 c is configured to measure gaspressure at the discharge 208. The inlet 206 is in fluid communicationwith the discharge 208 through a recycle valve 212 and a gas cooler 250(e.g., heat exchanger). In some embodiments, the recycle valve can be asliding stem turbomachinery control valve, a rotary turbomachinerycontrol valve, a guide vane, or any other appropriate turbomachinevalve.

In the example compressor system 200, an electric actuator 213 isconfigured to actuate the recycle valve 212. The electric actuator 213is an all-electric, high performance actuator. In some embodiments, theelectric actuator 213 can start moving the recycle valve 212 morequickly (e.g., about 25 mS typical) than is possible with the fluidactuators 113 and 117 of FIG. 1. In some embodiments, the electricactuator 213 can move the recycle valve 212 from closed to fully open inabout 0.3 to 0.6 seconds, although in some embodiments longer times mayoccur when actuating larger valves. In some embodiments, the electricactuator 213 may actuate the recycle valve 212 through a mechanicalcoupler or a fluid circuit.

In some embodiments, use of the electric actuator 213, rather than therelatively slower fluid actuators 113 and 117 of FIG. 1 allows thecompressor system 200 to be operated more efficiently than thecompressor system 100. In general, the closer that the compressorsystems 100, 200 can be operated on the operating map to thedeltaP/deltaQ surge line without actually reaching zero, the moreefficient the compressor systems 100, 200 can be. However, to preventthe flow-rate from being reduced to the extent that the operatingconditions actually reach a point along the operating map wheredeltaP/deltaQ=0, safety margins away from the surge line are generallyused. The magnitudes of these safety margins are at least partlyproportional to the amount of time needed for their correspondingcompressor systems to take corrective, anti-surge actions beforedeltaP/deltaQ reaches zero. Use of the electric actuator 213 reduces theamount of time needed to respond to conditions that are indicative ofsurge (e.g., compared to the fluid actuators 113 and 117), and allowsthe compressor system 200 to be operated safely closer to the surgeline. By operating closer to where deltaP/deltaQ=0, the compressorsystem 200 can operate more efficiently than the compressor system 100.

In some embodiments, the recycle valve 212 can be a high turn down valvethat can be modulated near the fully closed position without causingdamage to the internal metering elements of the recycle valve 212 due tohigh throttling conditions. In some embodiments, the recycle valve 212can includes noise reduction trim, either within the recycle valve 212or externally, depending upon operational requirements.

To prevent surge conditions, the electric actuator 213 of the examplecompressor system 200 includes an at least partly integrated anti-surgecontroller configured to receive surge parameter values, calculateproximity to surge control line, and take corrective control actions.The surge parameter values are based on measurement signals receivedfrom a collection of system sensors and feedback devices. In theillustrated example, the electric actuator 213 receives measurementsignals from the sensors 230 a-230 c.

To protect compressor from repeated surge, the electric actuator 213 ofthe example compressor system 200 includes an at least partly integratedsurge detection system configured to receive surge parameter values,detect surge conditions, and/or take corrective safety actions. Thesurge parameter values are based on measurement signals received from acollection of system sensors and feedback devices. In the illustratedexample, the electric actuator 213 receives measurement signals from thesensors 230 a-230 c. In some embodiments, different and/or additionalsensors may be used (e.g., temperature, torque, speed, vibration).

The fully integrated surge controller of the electric actuator 213 ofthe example compressor system 200 is programmed and dynamically matchedto the characteristics of the recycle valve 212 and the flow measurementsystem of the example compressor system 200 (e.g., the sensors 230 a-230c) such that the total system dynamics of the compressor system 200 arewell controlled and predictable.

If the electric actuator 213 determines that a surge event is occurring,the electric actuator 213 may directly or indirectly control a safeguardoperation. For example, the electric actuator can actuate the recyclevalve 212 to allow compressed gas at the discharge 208 to flow back tothe inlet 206 through the recycle valve 212 and the gas cooler 250 torelieve the surge condition. In another example, the electric actuator213 may provide signals that can be used to trigger other remedialactions, for example, such as a controlled reduction or shutdown of theprime mover 204. In some embodiments, the electric actuator 213 may alsoinclude functions such as surge control, choke control, steam turbineextraction control, gas turbine speed control, steam turbine speedcontrol, compressor guide vane capacity control, compressor inletthrottle valve capacity control, or combinations of these and/or anyother appropriate functions for compressor system control.

In some embodiments, the surge controller of the electric actuator 213can include a communication port that is configured to providecontroller operations information through the communications port. Asecond actuator can be configured to actuate a second valve of a secondturbomachine, and a second controller can be at least partiallyintegrated with the second actuator or the second valve. The secondcontroller can include a second communication port configured tocommunicate with the first communication port and receive controlleroperations information, and include circuitry configured to perform atleast one of a control operation or a protection operation for thesecond turbomachine based at least in part on the received controlleroperations information. For example, the electric actuator 213 mayprovide information to an electric actuator of another compressorsystem.

In some embodiments, the surge controller of the electric actuator 213can include a communication port that is configured to providecontroller operations information through the communications port. Asecond actuator can be configured to actuate a second valve of thecompressor system 200, and a second controller can be at least partiallyintegrated with the second actuator or the second valve. The secondcontroller can include a second communication port configured tocommunicate with the first communication port and receive controlleroperations information, and include circuitry configured to perform atleast one of a control operation or a protection operation for thecompressor system 200 based at least in part on the received controlleroperations information.

FIG. 3 is flow chart that shows an example of a process 300 forprotecting a turbomachine system. In some implementations, the process300 can be used to protect the example compressor system 200 of FIG. 2.

At 310, a first controller at least partially integrated with a firstvalve receives a first turbomachine parameter of a first turbomachinefrom a first field sensor. For example, the compressor system 200includes the electric actuator 213 which is configured to receivefeedback from the sensors 230 a-230 c.

At 320, the first controller determines at least one of a controloperation or a protection operation for the first turbomachine, based atleast in part on the received first turbomachine parameter. For example,the electric actuator 213 can receive feedback from the sensors 230a-230 c and determine that a surge event is underway (e.g.,deltaP/deltaQ is within the predetermined safety margin around the surgeline).

At 330, the first actuator at least partially integrated with the firstvalve or the first controller actuates the first valve to perform thedetermined control operation or protection operation for the firstturbomachine. For example, the electric actuator 213 can actuate therecycle valve 212 in an attempt to remedy the surge condition. In someimplementations, at least one of the control operation or the protectionoperation for the first turbomachine can include actuating the firstvalve to control flow of fluids to an integral or adjacent heatexchanger in fluid communication with the valve and configured to coolfluids that are passed through the valve. For example, the recycle valve212 can be actuated to allow compressed gasses to pass through the gascooler 250 and on to the inlet 206.

In some embodiments, the process 300 can include providing, by the firstcontroller, controller operations information through a firstcommunications port, receiving, at a second communications port of asecond controller at least partially integrated with a second valve of asecond turbomachine or a second actuator configured to actuate thesecond valve, the controller operations information, and actuating, bythe second actuator, the second valve perform at least one of a controloperation or a protection operation for the second turbomachine, basedat least in part on the received controller operations information. Forexample, the electric actuator 213 can provide control signals toanother electric actuator of another compressor system 200 to causeanother recycle valve to be actuated.

In some embodiments, the process 300 can include providing, by the firstcontroller, controller operations information through a firstcommunications port, receiving, at a second communications port of asecond controller at least partially integrated with a second valve ofthe first turbomachine or a second actuator configured to actuate thesecond valve, the controller operations information, and actuating, bythe second actuator, the second valve perform at least one of a controloperation or a protection operation for the first turbomachine, based atleast in part on the received controller operations information. Forexample, the electric actuator 213 can provide control signals toanother electric actuator of the compressor system 200 to cause anotherrecycle valve of the compressor system 200 to be actuated.

Although a few implementations have been described in detail above,other modifications are possible. For example, the logic flows depictedin the figures do not require the particular order shown, or sequentialorder, to achieve desirable results. In addition, other steps may beprovided, or steps may be eliminated, from the described flows, andother components may be added to, or removed from, the describedsystems. Accordingly, other implementations are within the scope of thefollowing claims.

What is claimed is:
 1. A compressor anti-surge system comprising: afirst actuator configured to actuate a first valve of a firstturbomachine; and a first controller at least partially integrated withthe first actuator or the first valve, and comprising circuitryconfigured to perform at least one of a control operation or aprotection operation for the first turbomachine.
 2. The compressoranti-surge system of claim 1, wherein the first actuator is configuredto actuate the first valve through a mechanical coupler or a fluidcircuit.
 3. The compressor anti-surge system of claim 1, furthercomprising a first field sensor configured to sense a first turbomachineparameter of the first turbomachine; wherein the first controller isfurther configured to receive the first turbomachine parameter from thefirst field sensor and perform at least one of a control operation or aprotection operation for the first turbomachine, based at least in parton the received first turbomachine parameter.
 4. The compressoranti-surge system of claim 1, wherein the valve is a sliding stemturbomachinery control valve, rotary turbomachinery control valve, or aguide vane.
 5. The compressor anti-surge system of claim 1, furthercomprising an integral or adjacent heat exchanger in fluid communicationwith the valve and configured to cool fluids that are passed through thevalve.
 6. The compressor anti-surge system of claim 1, wherein: thefirst controller further comprises a first communication port and isconfigured to provide controller operations information through thefirst communications port; a second actuator configured to actuate asecond valve of a second turbomachine; and a second controller at leastpartially integrated with the second actuator or the second valve, asecond communication port configured to communicate with the firstcommunication port and receive controller operations information, andcomprising circuitry configured to perform at least one of a controloperation or a protection operation for the second turbomachine, basedat least in part on the received controller operations information. 7.The compressor anti-surge system of claim 1, wherein: the firstcontroller further comprises a first communication port and isconfigured to provide controller operations information through thefirst communications port; a second actuator configured to actuate asecond valve of the first turbomachine; and a second controller at leastpartially integrated with the second actuator or the second valve, asecond communication port configured to communicate with the firstcommunication port and receive controller operations information, andcomprising circuitry configured to perform at least one of a controloperation or a protection operation for the first turbomachine, based atleast in part on the received controller operations information.
 8. Amethod of responding to compressor surge comprising: receiving, at afirst controller at least partially integrated with a first valve andfrom a first field sensor, a first turbomachine parameter of a firstturbomachine; determining, by the first controller, at least one of acontrol operation or a protection operation for the first turbomachine,based at least in part on the received first turbomachine parameter; andactuating, by a first actuator at least partially integrated with thefirst valve or the first controller, the first valve to perform thedetermined control operation or protection operation for the firstturbomachine.
 9. The method of claim 8, wherein the first actuator isconfigured to actuate the first valve through a mechanical coupler or afluid circuit.
 10. The method of claim 8, wherein the valve is a slidingstem turbomachinery control valve, rotary turbomachinery control valve,or a guide vane.
 11. The method of claim 8, wherein at least one of thecontrol operation or the protection operation for the first turbomachinecomprises actuating the first valve to control flow of fluids to anintegral or adjacent heat exchanger in fluid communication with thevalve and configured to cool fluids that are passed through the valve.12. The method of claim 8, further comprising: providing, by the firstcontroller, controller operations information through a firstcommunications port; receiving, at a second communications port of asecond controller at least partially integrated with a second valve of asecond turbomachine or a second actuator configured to actuate thesecond valve, the controller operations information; and actuating, bythe second actuator, the second valve to perform at least one of acontrol operation or a protection operation for the second turbomachine,based at least in part on the received controller operationsinformation.
 13. The method of claim 8, further comprising: providing,by the first controller, controller operations information through afirst communications port; receiving, at a second communications port ofa second controller at least partially integrated with a second valve ofthe first turbomachine or a second actuator configured to actuate thesecond valve, the controller operations information; and actuating, bythe second actuator, the second valve to perform at least one of acontrol operation or a protection operation for the first turbomachine,based at least in part on the received controller operationsinformation.